The present invention relates to a method of updating the system time of the timer of a data processor system. More specifically, the present invention involves using the time information of a message to update the system time of a data processor.
The exact operation of a data processor system requires a precise time base. It is common to provide a clock component with a high-precision quartz oscillator generating the system clock cycle in a data processor system for forming a time base which the operator of the data processor system can xe2x80x9csetxe2x80x9d either once or as necessary in the case of deviations of time with respect to an official time, using a different time base.
European Patent EP 0 691 598 A2 discloses a method of and an apparatus for updating the time of a system clock in a consumer electronics unit. According to the method, transmitted real time information is used for setting the clock, which can be extracted from high-frequency radio signal, in that case from the video text signal.
The disadvantage of this system resides in the fact that many radio services do not contain such a time information.
In overcoming the deficiencies of prior art, the present invention proposes a method that may be employed in a data processor system to update the time base of the data processor system, while security in terms of manipulation or tampering and freedom of maintenance are ensured, whenever a time information is not regularly transmitted in the radio service. The present invention also proposes an apparatus for carrying out the method.
A reduction of the hardware for the generation of data required for the operation of a data processor system can be achieved when such data is extracted from another electronic means where it is available already only under defined conditions in the course of operation, and can be made available in the original data processor system, too, whenever this will be necessary.
In the case of an SMS message to be communicated between two subscribers via the SMA service (Short Message Service)xe2x80x94which constitutes one element in the service programmexe2x80x94in compliance with the international GSM Standard (Global System for Mobile Communication), data is available due to a digital timing marker including the respective actual date and time information, by means of which this message is supplemented in the locally active base station of the GSM radio network by the time of transmission, which data may be expediently used also for another systemxe2x80x94independently of the contents of the SMS message communicated. The time information is advantageously highly precise because the GSM providers use clocks with a high precision level, preferably in view of rate accounting.
In accordance with the present invention the timing marker containing the date and time information of a previously transmitted SMS message, which is received via the GSM radio network, is internally selected as digital signal component in the system of the subscriber station and used as a time base of a data processor system. For the transmission of the signal component forming the time marker from the subscriber station to the data processor system a separate data communication line is used.
According to the present invention, the subscriber station connected to the data processor system sends an SMS message to itself for updating the timer of the data processor system. In this concept the fact is expediently made use of, on the one hand, that in a radio networkxe2x80x94in distinction from a line-switching systemxe2x80x94the time interval within which reception is possible again already after transmission of a message is shorter than the time which such a message takes for being emitted by the radio service again after reception because mostly the message is additionally buffered in the associated message server.
Moreover, the method according to the present invention presents the advantage that the length and the contents of the message are not awarded any importance for enabling the timing marker to be imprinted on the message in the subscriber station. In accordance with an exemplary embodiment of the present invention, an individual identifier is used as contents of the SMS message which allows for a recognition of the emitted message.
In accordance with the method of the present invention, upon receipt of the SMS message, the subscriber station performs a system-internal selection of the digital signal component carrying the date and time information in the SMS message, and this timing marker is used for updating the system time of the timer upon communication to the data processor system.
When one and the same subscriber station is sender and the receiver of an SMS message, the method makes it possible in a simple manner to obtain this date and time information for the data processor system as required by sending an SMS message.
When the subscriber station receives the call from a third party during the transit time of an SMS message sent by itself the SMS message will not be lost because the network operator buffers the SMS message and forwards it together with the time information then actual to the subscriber station after the end of the intermediate call. On the other hand, it is also possible that the SMS message will be communicated outside the usual traffic channels so that the timing marker can be processed in the mobile station even during the transmission of the call of such a third party and the corresponding data communication to the data processor system can be performed.
In accordance with another preferred embodiment of the method of the present invention, a time offset is compensated by a correcting factor, which offset inevitably derives, on the one hand, from the transit time between the GSM base station in the respective radio cell of the network operator and the subscriber station, and which, on the other hand, is due to signal delays caused by an optimum utilisation of the used communication channels. The application of such a correction factor is expedient particularly when there is a need for a highly precise time setting for the data processor system.
In correspondence with an exemplary embodiment of the present invention, a time offset value is used as correcting factor for compensating the time offset which depends on the distance and the communication mode. This correcting factor has a magnitude of preferably four seconds as practicable average value with due consideration of standardised protocols for the implementation of the service programme for application-related communication between a mobile subscriber and another user of a GSM radio network.
According to an improvement of the present invention, a correcting value is determined in the mobile system on the basis of several setting operation for the system-internal clock in correspondence with the method, which value is suitable for preventive correction of the internal time base. It is thus possible to save costs by extending the setting intervals for the system-internal clock.
In correspondence with yet another exemplary embodiment of the present invention, the transmission of an information in the format of an SMS message from the subscriber station of the data processor system, which is completed with the subscriber station""s own address as destination address, is always caused only when an SMS message from an external station has not been received within a definable interval and a check or resetting of the system time is necessary.
In the broadest sense of the invention it is also possible to use any information emitted by an external action in the format of an SMS message for setting the system-internal clock.
In accordance with the present invention, the apparatus used for implementing the aforedescribed method of updating the system time of the timer in a data processor system includes a base station of a GSM radio network and a subscriber station authorised for radio communication in this network and associated with the same radio cell, which subscriber station is connected to the data processor system by means of a data communication line.
In the subscriber station a GSM module is provided for transmitting and receiving a SMS message in compliance with the telephone service programme of the GSM radio network.
According to another preferred embodiment of the invention, the data processor system includes a first electronic means for the transmission of an SMS message to itself at selectable time intervals. This feature ensures in a simple manner that a signal for updating the time base will be periodically available for setting the system time of the timer.
In correspondence with an exemplary embodiment of the present invention, a clock pulse generator and a memory unit are provided as first electronic means, which memory can be activated by the clock pulse generator and from which the specific identifier of the data processor system as well as a short information is retrieved as contents of an SMS message which the data processor system then sends to itself.
According to another exemplary embodiment of the present invention the data processor system includes a second electronic means for programming the GSM module, which allows for the use of the services of other radio telephone networks if the latter offer a message transmission combined with time and/or date information.
In correspondence with another exemplary embodiment of the present invention, an apparatus is provided for implementing the method, wherein the data processor system is configured as mobile device. For this purpose various potential applications are expedient. For instance a portable computer can be coupled to a radio telephone via a plug and play connector, or a portable computer equipped with a telecommunication means. In an equally advantageous manner, it is possible to use an SMS message for generating the time base for the system time of the timer of the data processor system of an automotive vehicle.